Update CHANGELOG.md for 11.1.5
Update CHANGELOG.md for 11.1.5

[ci skip]
dreampet/gitlab,mmkassem/gitlabhq,jirutka/gitlabhq,iiet/iiet-git,dreampet/gitlab,stoplightio/gitlabhq,mmkassem/gitlabhq,jirutka/gitlabhq,mmkassem/gitlabhq,iiet/iiet-git,axilleas/gitlabhq,stoplightio/gitlabhq,iiet/iiet-git,jirutka/gitlabhq,mmkassem/gitlabhq,axilleas/gitlabhq,axilleas/gitlabhq,jirutka/gitlabhq,stoplightio/gitlabhq,iiet/iiet-git,dreampet/gitlab,axilleas/gitlabhq,stoplightio/gitlabhq,dreampet/gitlab